Soldering-paste.



UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

Patented Nov. 14, 1905.

Application filed July 2, 1904. Serial No. 216,099.

To all whom it mayconcern:

Be it known that I, MAXIMILIAN LEISEL, a subject of the German Emperor,and a resident of Cologne-on-the-Rhine,Germany, have invented a new andImproved Soldering-Paste, of which the following is a full, clear, andexact description.

The soldering of metals is, as a rule, effected by applying a solderingmedium or flux on the place to be soldered in order to remove any oxidspossibly present or to prevent the formation of the same, after whichthe solder is usually applied with a solderingiron or the like andmelted, the said medium or flux enabling the solder to flow in thedesired manner. As a flux or soldering medium in the case ofsoft-soldering an aqueous solution of ammonium chlorid, zinc chlorid, orzinc ammonium chlorid is employed and in the case of hard-solderingborax, water-glass, glass-powder, or the like.

In order to produce finer solderings, the

solder is employed in the form of foil or powder alone or directly mixedwith the fluxes or soldering mediums mentioned above.

Soldering, for example, with ammonium chlorid or zinc-ammonium-chloridsolution the so-called soldering-water or soldering solution has beenfound in practice to possess the defect that the soldered places orseams become defective in the course of time on account of the formationof residues which are difiicult to remove and that during solderinground spots or stains arise which can only be removed by corrosion,bybiting with acids, or the like and that long joints or seams to besoldered cannot be soldered without a renewal of the soldering-water.The reason of all these defects is that the water of the soldering wateror solution evaporates more quickly than the soldering metal is melted,so that the soldering medium becomes dry before the solder is melted,whereby the formation of oxid is especially produced, the flow of thesolder is impaired, and the solderedjoint subsequently becomesdefective. Consequently in electrical engineering soldering withsoldering mediums has for some years been pro hibited, and in Germanysoldering with resin andytin has become the general practice in order toobtain durable solderings, although such a process is alwaystroublesome. In

order to perform this method of working as economically as possible,solder sticks have been produced which consist of a hard homogeneousmixture of resin and particles of tin solder with or without theaddition of another soldering medium or flux,such as salammoniac, forexample. With such a solder stick, however, very fine solderings or thesoldering of places accessible only with very great difiiculty naturallycannot be effected, and losses in the soldering materials cannot easilybe avoided.

All the defects mentioned above in connection with the well-knownsoldering processes are avoided by the soldering-paste materialaccordingto the present invention, which a1- lo'ws also employing evenammonium chlorid insolution for solderings, which are free fromobjection, and besides the customary soldering metals such metals ashitherto have not been applicable for soldering purposes and have beenunknown for this purpose.

The soldering material according to the present invention consists,essentially, of such metals as can be converted into an extremely finemetal powder particularly, for example, by reduction into dust byelectrolysis or by mechanical means, such as blastingor the like. Suchmetals are, for instance, bismuth, tin, lead, zinc, antimony, I brass,copper, nickel, aluminium, silver, gold, cobalt, iron, bronze, and soon, or their alloys. In order to prevent the oxidation of such metalpowder or dust, such finely-divided metal being as is well known, veryreadily oxidized, the metal powder according to the present invention issurrounded or enveloped with a fluid soldering medium or flux whichremains fluid until use and until the metal solder or the soldering saltor substance in the same is meltedthat is to say, the said solderingmedium does not evaporate before use and before the metal solder or theadded soldering salt or flux (for example, borax) is meltedso that thefine soldering-powder is surrounded by a fluid material until it ismelted. As an especially advantageous material, whether soft or hardsoldering material is to be manufactured, may be mentioned a solution ofan acid-free soldering salt, such as ammonium chlorid or borax,water-glass, or the like in glycerin. According to the quantity of thesaid solutions employed the soldering material of the present processforms a more or less stiff paste. The action of the same is as follows:

If the present soldering-paste consists of softsolder. powder, (tin orthe like,) ammonium chlorid, and glycerin, the glycerin does notevaporate before the solder is melted, as it possesses a boiling-pointwhich is' higher so that the solder remains surrounded by the fluidsoldering medium or flux'and is protect- -ed from oxidation until itismeltd. Also the added soldering salt does not become dried up beforethe solder is melted, so that a renewal of the soldering medium or fluxwhen soldering long joints is not necessary, as the formation of oxidson the place to be soldered is prevented, and consequently the flow ofthe solder is not impaired. Such apaste can also consist of a suitablemetal powder impregnated with a solution of colophonium in oils or thelike.

If the soldering-paste, for example, consists of a hard-soldering metal,a flux, such as horax, and glycerin, the glycerin does not evaporatebefore the borax is melted, which in the melted condition in its turnsurrounds the metal powder and protects the same from oxidation untilsaid powder is melted.

The present soldering-paste possesses, in addition to the advantagespreviously mentioned, the further advantages that it works not onlyperfectly uninjuriously and leaves behind no after effects-such as areleft, for example, by soldering materials prepared with aqueous ammoniumchlorid or zinc-chlorid solutionsbut that places accessible only withvery great difliculty and joints of any length can be sol-v dered withit without a renewal of the soldering medium or flux being requisite, asis customary. Moreover, it leaves behind no black or dark spots orstains which after the soldering processmust be removed by corrosi'on,biting with acids, or the like, and it permits the finest cracks,fractures, and chinks and the like to be filled up, and it can beapplied in the thinnest layers. Further, it possesses the additionaladvantage that it is perfectly permanent, does not dry up, and can bemade as thin and fluid,as desired by the addition of glycerin or evenwater. Also with a paste manufactured in this manner out ofsoft-soldering metal or alloy almost all metals can be soldered, inparticular such as hitherto it has been possible to solder only withdifficulty.

By employing the metal solder in an extremely finely divided conditiononly a slight amount of heat is requisite for soldering, as it, can bemelted in such a condition much more easily and quickly. Also there is asaving in solder, as one need apply only the requisite amount, thisbeing effected with a brush, the hand, or the like. In the case ofsoft-soldering the soldering can be effected with a simple spirit flameand is consequently so glycerin other organic substances can alsonaturally be employed, in so far as they produce the intended eflect,and consequently have a boiling-point which is higher than thevmelting-point of the soldering metal or of the soldering salt. Thushydrocarbons, alcohols,

&c.,vaseline-oil, or otheroils and fats, stearin,

ceresin, and the like, or mixtures thereof, all boiling at a hightemperature, can be employed. Corresponding pastes or material are thenobtained, which can be worked into pastes by means of water, oil, andother diluting or dissolving means.

What I claim is' 1. The herein-described soldering-paste, consisting ofa mixture of fine soldering metal dust and a solution in glycerin of anacid-free flux, which solution in heating leaves no acid residues,substantially as described.

2. The hereinbefore-described solderingpaste, consisting offinely-divided soldering metal, glycerin and a soldering flux free fromacid, as described.

3. The hereinbefore-described solderingpaste, consisting offinely-divided soft-soldering metal, glycerin and a soldering flux freefrom acid, as described.

4:. The herein-described soldering-paste consisting of a mixture ofsoft-soldering metal dust, glycerin, and an ammoniacal soldering salt.

Intestimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

MAXIMILIAN LEISEL.

Witnesses:

J 0H. SoHoLz, WILLIAM Russians.

